Fundamental characteristics of organic radicals used in biomedical applications

Organic radicals are highly reactive and instable structures in biology, and by virtue of their unique chemical properties and paramagnetism, they have found widespread exploration in physical, chemical, and biological fields. However, most open-shelled radicals are too short-lived and thought to all be bad actors in the membrane of cells of damaging biologically relevant molecules (DNA, RNA, lipids, proteins carbohydrates, etc.) and are now known to play a central role in many enzymatic reactions, which make them very important to cell damage and homeostatic disruption mechanisms. Thus many researchers reported several works to develop stable radical-containing materials. This chapter hotspots the essential characteristic of organic radical materials and spotlights their applications in biomedical fields, in particular for bioimaging, biosensing, photo-triggered therapies, and also their future development is also discussed.